Four people have been killed and eight injured in China's far-western region of Xinjiang, government officials said.

One person is under arrest following the deaths on Thursday afternoon in Korla, central Xinjiang.

A regional government spokesman said on Friday the incident happened in the city's Golden Triangle, a commercial district. "A criminal attacked local people … the case is under investigation and the identity and ethnicity of the criminal and victims is not confirmed yet."

The region has experienced repeated outbreaks of violence amid ongoing tensions between Han Chinese and Muslim Uighurs, many of whom chafe at controls on their religion and culture and the impact of large-scale Han migration into the region. Some want an independent state.

Unconfirmed online accounts, some claiming to be from witnesses, suggested Thursday's killings stemmed from a row in a video arcade or shop. Others suggested there may have been an ethnic dimension. Several of the posts were quickly deleted.

Radio Free Asia said police in Korla confirmed a citywide security clampdown following the deaths.

An officer who answered the phone at the municipal police incident room suggested one or more Uighurs had attacked Han Chinese but declined to give details.